Very hot HW, no CH !

Jeremyb123 · 1 Nov 2006

HW comes on fine, though it is very hot indeed, even with the therostat on the HW tank turned to minimum.No heating at all,timings set OK, room thermostat turned on, pump seems to work, as when the screw is turned you can hear the water moving in all rads. Bleed rads, clear water coming out under pressure.Have a Honeywell F40027 3 port valve, when this is turned to manual nothing happens.Pipe coming out of HW tank to 3 port valve is stonecold, as are pipes coming from 3 port valve ? Does the valve need replacing ?

Handy Manny · 2 Nov 2006

Had the same problem a few months ago, had a replacment valve to try out. Also the DHW sensor/Ch sensors were faulty so I replaced these first.
When I removed the valve it was basically blocked with sludge. Once this was cleaned up and refitted I flushed the system through, no problems since.

Jeremyb123 · 2 Nov 2006

Thanks for that.

I don't think it is sludge, as the water coming out of the radiators was clear.

What is a DHW sensor ?

The honeywell thermostat in the kitchen has two lights, one for temp reached and one for temp below, so I think this is working OK.

I can't understand that when I move the 3 port valve to manual nothing happens ?

I'm going to take of the motor to it tonite and try and move the spindle - is that a good idea ?

OliverHill · 2 Nov 2006

You say the hot water is very hot regardless of the tank stat and that the pipe work from the tank to the valve is stone cold. Seems a bit odd to me. You don't by any chance have the tank emersion heater on 24/7? These arn't normally connected to the tank stat and will just heat until they reach their own thermal cut off - which is normally very hot indeed.

Sounds to me that everything is working except the boiler isn't doing any water heating. What kind of boiler is it?

MANDATE · 3 Nov 2006

When dealing with a 3 port mid position valve, problem likely to be valve not moving to CH only position or if it does move to the correct position faulty microswitch prevents power getting to boiler pump.
By all means remove head and check spindle for stiffness, also observe motor/quadrant as you try the various selections. HW only HW/CH and CH only. If motor does not move at all then room stat should be checked.
If CH is fine when HW is also called for, it proves valve does move to mid position. To prove this point you will have to turn cylinder stat up a little or run off some Hot Water to create a demand for HW, otherwise you'll have to wait till HW in cylinder cools down

Agile · 3 Nov 2006

Oliver gets six replies to the question he posted himself yesterday and he is now about to give advice to others!

Jeremyb123 · 8 Nov 2006

Thanks everyone for their contributions.

I (thought ) I had checked everything,over and over again, but after some of your comments I checked again.
It turns out the emersion was on 27/7, for at least 18 months, so not only was I getting boiling hot water, I was also paying thru the nose for it ! So once this was turned off nothing else was happening. As a last ditch attempt, before calling out the plumber, I checked the gas boiler behind the fire - No Pilot light ! Once this was lit the whole system fired up like a dream ! Moral - Always check the very basics !

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Very hot HW, no CH !

Similar threads